78 



CLIMATIC CYCLES AND TREE-GROWTH. 



In seeking further evidence of sunspot correlation, advantage was 

 taken of certain statistics recorded while measuring the various sec- 

 tions. Before making the measures or identifying the rings in any way, 

 the groups of rings larger than the average were sought out and 



10 



iZSP 



ISOO 



10 



I85O 



IQOO 



FIG. 26. Dates of large rings in 80 European trees compared with sunspot curves. 

 Ordinates give number of trees in total of 80 showing maxima in respective years. 



1710 



Windsor, Vermont, uroup 

 (II Sections) 



(Sunspot curve displaced I year to left) 



1810 



(Sunspot curve 



1850 



displaced 3 years to left ) 



2.5 



20 



1.5 



1.0 



2.0 



1.5 



1.0 



1^00 I9IO 



FIG. 27. Tree-growth at Windsor, Vermont, showing measures uncorrected; same 

 standardized and smoothed, and sunspot numbers displaced 3 years to left. 



